A Fine Gael bill proposing that bye-elections be held within six months of a vacancy arising in a constituency has been defeated in the Dáil.
The Government's side won the vote 72-68.
Bye-elections are due in three constituencies: in Dublin South, Waterford and Donegal South West.
The Donegal South West seat has remained vacant for nearly a year.
Fine Gael Environment Spokesman Phil Hogan said the Bill would take away from any Government the decision on holding a bye-election.
Fianna Fáil TD Seán Power said he could see merit in a Fine Gael proposal to hold by elections within 6 months of a vacancy arising.
Deputy Power said that the people of Donegal South West need their rightful representation but that the Fine Gael proposal needs more 'flexibility'.
The Bill was also supported by three Independents - Joe Behan, Finian McGrath and Maureen O'Sullivan and was voted last night.